BOSTON — From the latest troubles on the MBTA to the constant traffic on the roads, transportation advocates are pushing for more investments, even if some of the money may have to come out of their pockets. They gathered at the state house Tuesday to urge lawmakers to support ideas such as congestion pricing, raising the gas tax and adding more fees to ride shares. They said this could help generate the revenue needed to fix the transportation system and well as pump millions into the MBTA.